1. Field of the Invention
The invention relates to an actuating head of a double-acting pump for ejecting a product from a container, wherein the container has an outlet duct leading to an ejection opening and a closing piece biased by a spring is arranged in the outlet duct, wherein the closing piece in a closed position thereof directly seals the ejection opening under the force of the spring, and wherein the pressure of the product exerted when the double-acting pump is actuated releases the flow of the product through the outlet duct and through the ejection opening against the force of the spring.
2. Description of the Related Art
In a known actuating head of this type (DE 201 03 144 U1), an outlet duct section extends through the body of the actuating head up to a cylindrical space in a bore of the body which follows the outlet opening and in which the closing piece is sealingly guided. The construction of this outlet duct section is cumbersome. It requires a complicated molding tool if the body of the actuating head, as is usual, is manufactured of thermoplastic material. In addition, the outlet duct section must be constructed of two parts, wherein the two parts must be tightly connected to each other, either by welding or gluing, which is time-consuming and labor-intensive.
In another known actuating head (DE 27 09 796 B2), the closing piece is constructed as a valve slide which is slideable transversely of an inlet opening of on outlet duct located between the closing piece and the ejection opening. Arranged in the outlet duct in front of the ejection opening is a turbulence chamber. Through the ejection opening the outlet duct is in connection with the outside in any position of the closing piece. Accordingly, any product rest which has not been completely ejected from the outlet duct can come into contact with contaminating and harmful germs, bacteria or viruses contained in the ambient air and with aggressive gases which are harmful for the product, particularly ambient oxygen. Such harmful influences are especially undesirable or dangerous if the product is a foodstuff, a medicament, deodorant or another product which is taken in or picked up by a person, even if only a small contaminated product rest remains in the actuating head. During the next actuation after a long period of no actuation, such a contaminated product rest could be ejected together with the product and could endanger the health of the user.
It is the object of the invention to provide an actuating head of the above-described type which is simple to manufacture and in which the danger of a contamination of the product is essentially prevented.
In accordance with the invention, this object is met in an actuating head of the above-described type in that a first outlet duct section following the ejection opening is surrounded by a tube in which the closing piece is sealingly slideably guided and which is inserted into a bore in the body of the actuating head, wherein the bore defines between itself and the tube an annular space which forms a second outlet duct section, wherein the second outlet duct section is connected through a third outlet section traversing the wall of the pipe to the first outlet duct section.
In this solution, the three above-mentioned outlet duct sections are defined by the bore and the tube, wherein the tube only has to be inserted tightly into the bore. Accordingly, shaping of the actuating head is very simple, independently of its material which preferably is thermoplastic material. In addition, a product rest present in the outlet duct cannot be contaminated either in the open position or in the closed position of the closing piece: in the open position which lasts only a short time during the product ejection, the product rest would be substantially ejected, and in the closed position the outlet duct is completely blocked to the outside by the closing piece. Consequently, a product rest remaining in the outlet duct cannot come into contact with harmful germs, bacteria, viruses, etc. and with harmful materials, such as gases, particularly ambient oxygen.
It is preferably ensured that the closing piece includes a piston which seals the closing piece relative to the inner side of the outlet duct, wherein the piston has a piston rod which in the closed position of the closing piece projects with an end portion thereof tightly in the ejection opening. The closing piece not only acts as a closing piece, but also as a pressure piston which, after the actuation of the double-acting pump by the actuating head, ejects the product remaining in the outlet duct under the force of the spring through the ejection opening and simultaneously blocks the ejection opening.
Moreover, the portion of the piston rod adjacent the end portion may have a greater diameter than the ejection opening and, in the closed position of the closing piece, rests against the inner edge of the ejection opening under the force of the spring. The portion of the piston rod having the greater diameter additionally comes into sealing contact with the inner edge of the ejection opening during the closing movement of the closing piece under the force of the spring with its shoulder surface extending from the larger to the smaller diameter. Simultaneously, the closing movement is limited.
The piston preferably has a circumferential sealing lip which permits passage of the product only in the direction toward the ejection opening. On the one hand, the sealing lip facilitates the passage of air from the spring chamber into the outlet duct during the first actuation of the actuating head, so that the product pressure essentially only has to overcome the spring force during the product ejection. The air which penetrated from the spring chamber into the outlet duct would during the first actuation be partially mixed with the product quantity which has been ejected and which will be ejected during the next actuation. However, during the second and all following actuations, no additional air would penetrate from the spring chamber into the outlet duct because the excess pressure of the air has already been eliminated and the sealing lip permits only the air passage in one direction and, thus, no renewed penetration of air into the spring chamber. In the same manner, penetration of the product through the sealing lip into the spring chamber is prevented.
The sealing lip may particularly be constructed as a cup-shaped material. The cup-shaped material is additionally pressed by the product pressure against the inner side of the outlet duct and, thus, ensures a particularly high sealing effect.
The closing piece is preferably of a rubber-elastic material with an excess dimension of the end portion relative to the diameter of the ejection opening. As a result of this configuration, the end portion of the piston rod rests particularly tightly in the ejection opening in the closed position of the closing piece. This results in a particularly high sealing effect of the end portion in the ejection opening.
The rubber-elastic material may be a plastic material. Such a material facilitates a simple construction of the closing piece as a single piece.